Mesoporous TiO2 thin films were prepared on aluminum substrate via the reverse micellar method (RM-TiO2) and sol–gel method (SG-TiO2), respectively. It was found that the mesoporous RM-TiO2 thin films exhibited a better photocatalytic performance than that of SG-TiO2 in the degradation of acetone in air and photo-induced hydrophilicity. This was attributed to the fact that the RM-TiO2 thin films had higher specific surface area and porosity than that of SG-TiO2. The larger surface-to-volume ratio of mesoporous RM-TiO2 thin films can serve as a more efficient transport path for gaseous reactants and products in photocatalytic reactions, thus improving the photocatalytic activity. The photocatalytic performance and hydrophilicity of RM-TiO2 thin films coated on different substrates were also compared. The aluminium-supported samples showed a slower photocatalytic rate than those on quartz and stainless steel in the degradation of acetone because aluminum ions diffused from the substrate and acted as a charge recombination center. However, the hydrophilic property of the TiO2/Al sample was superior to those on quartz and stainless steel substrates, probably due to its higher surface roughness and hydroxyl content.